Light projection device and light source support means therefor



Ap vril29,196 9 M.HONEYCUTT 3,441,771

LIGHT PROJECTION DEViCE AND LIGHT SOURCE SUPPORT MEANS THEREFOR Filed Sept. 1. 1966 K K)" /7 A? '3/ Z 26 8 N /5 /4 ITWVTTTCDT-I Murray l-loneycwt t by M 6 His A tiznvne g United States Patent 3,441,771 LIGHT PROJECTION DEVICE AND LIGHT SOURCE SUPPORT MEANS THEREFOR Murray Honeycutt, Lyndhurst, Ohio, assignor to General Electric Company, a corporation of New York Filed Sept. 1, 1966, Ser. No. 576,680 Int. Cl. HOlj 5/16; H01k 1/28, 1/18 U.S. Cl. 313-113 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates in general to light projection devices of the type comprising an electric lamp mounted within an outer enclosing envelope, and more particularly to a support structure for the lamp of such a device.

In the service for which certain types of electric lamps are intended, the lamp is normally subjected to constant or prolonged periods of severe vibration. This is particularly true, for instance, in the case of electric lamps employed for aircraft service such as aircraft landing lamps. For acceptable use in such service, the lamp must be capable of satisfactorily withstanding the severe vibrations to which it is subjected without early rupture and failure thereof.

The light projection devices conventionally employed heretofore as airplane landing lights have been in the form of a self-contained reflector type incandescent lamp comprised of a sealed pressed-glass envelope formed with a reflector portion and having exposed therewithin an incandescible filament such as a tungsten wire coil. There are, however, certain compact type electric lamps which have been introduced on the market of late which have a greatly increased light output and useful life as compared to prior type lamps such as renders their use highly desirable in airplane landing lamps. One such improved type electric lamp is the well-known halogen cycle incandescent filament lamp which has a high efliciency for a long useful life with virtual freedom from bulb blackening, all made possible by operating a tungsten filament in a compact bul-b containing in addition to the usual gas filling, a quantity of a halogen which serves as a regenerative getter. During operation of the lamp, the walls of the compact bulb are heated to a high temperature, and tungsten vapors normally volatilized from the filament and deposited on the bulb walls as a dark coating or blackening combine chemically with the halogen to form a tungsten-halogen compound which migrates to the vicinity of the hot filament where it is then dissociated to release tungsten which redeposits on the filament, the

halogen returning to the bulb walls to repeat the cycle.

Such lamps, employing iodine as the regenerative getter, are disclosed and claimed in U.S. Patent 2,883,571, Fridrich et al.

The ordinary way of mounting a compact electric lamp such as described above in the envelope of a light projection device such as the conventional airplane landing light is to simply attach the rigid lead-in conductors of the lamp to the two rigid lead-in or current-supply wires of the 3,441,771 Patented Apr. 29, 1969 light projection device so as to connect the lamp across the lead-in wires and firmly support it therefrom. However, light projection devices of such construction have proven to be unsatisfactory for use as an airplane landing light, the filaments of the electric lamps in such devices becoming excessively distorted and rupturing within a comparatively short period of lamp operating time and so causing early lamp failure.

It is an object of my invention, therefore, to provide a light projection device of the type having a compact electric lamp mounted within an outer enclosing envelope and which is capable of withstanding severe vibrational stresses during operation without being subject to early lamp failure.

Another object of the invention is to provide a light projection device of the above-mentioned type having a novel support structure for the electric lamp mounted within the outer enclosing envelope of the device.

Briefly stated, in accordance with one aspect of my invention, the compact electric lamp in a light projection device of the type referred to hereinabove is supported in place within the outer enclosing envelope of the device by three rigid supporting wires which extend into the outer enclosing envelope of the device in triangularly disposed relation to one another, the lamp being rigidly fastened across and supported from two of the supporting wires which also serve as current-supply wires for the lead-in conductors of the lamp, and being additionally braced against vibratory movement in the device by a pair of rigid bridge or brace members rigidly fastened to the third supporting wire and to respective ones of the current-supply wires of the device adjacent their points of connection to the lamp lead-in conductors. According to a further aspect of the invention, the brace members are secured to the third supporting wire at points which are spaced inwardly of the reflector portion of the outer enclosing envelope of the device relative to the supported lamp therein.

Further objects and advantages of my invention will appear from the following detailed description of a species thereof and from the accompanying drawing.

In the drawing, FIG. 1 is a horizontal sectional view of a light projection device according to my invention.

FIG. 2 is a fragmentary elevational view of the light projection device with the envelope thereof shown partly broken away to reveal the electric lamp and support means therefor within the envelope, and

FIG. 3 is a perspective view of the electric lamp and support structure of the light projection device.

Referring to the drawing, the invention is there shown as embodied in a self-contained reflector type electric lamp of the sealed beam type described and claimed in U.S. Patent 2,148,314, D. K. Wright, and comprising a sealed glass outer envelope or bulb 1 consisting of preformed pressed glass reflector and cover glass sections 2 and 3, respectively, sealed together at their peripheries by fusion, as indicated at 4. The concave inner surface 5 of the reflector section 2 is formed of approximately paraboloidal shape and is covered with a reflecting coating 6 of aluminum, silver or other similar light-reflective material. The envelope 1 is provided with an exhaust tubulation 7 communicating with the interior of the envelope through an exhaust aperture 8 in the envelope wall at the apex of the reflector section 2. After exhaustion of the envelope through the tubulation 7 and, if desired, introduction of a suitable gas filling such as nitrogen or argon, the tubulation 7 is sealed or tipped-off as indicated at 9.

Mounted within the envelope 1 and approximately centered at the focus of the reflecting surface 6 thereof is a compact electric lamp 10 which, in the particular case illustrated, is of the well-known halogen cycle type as disclosed in the aforesaid Patent 2,883,571 and comprising a tubular bulb or envelope 11 of glass or quartz containing a longitudinally extending filament 12 of coiled tungsten wire having a gas filling including a small quantity of a halogen such as iodine vapor and an inert gas such as nitrogen, argon, krypton, or xenon or mixtures thereof at a pressure of preferably at least several hundred millimeters of mercury, and even exceeding atmospheric. The iodine or other halogen vapor serves as a regenerative getter to maintain the walls of the lamp bulb 11 free from deposits of tungsten vaporized from the filament 12. In view of the requisite high operating temperature of such halogen cycle incandescent lamps wherein the walls of the lamp bulb 11 attain a temperature in excess of 250 C., for example about 500 C., the bulb 11 is made of glass of relatively high softening point, such as one of the well-known so-called hard glasses like borosilicate or alumino-silicate glasses, or quartz glass.

The coiled filament 12 is supported within the tubular bulb 11 in a position extending generally axially thereof, by a pair of lead-in conductors 13 which are hermetically sealed in compressed flattened pinch seal portions 14 of the bulb formed at the opposite ends thereof. The lead-in conductors 13 are provided with outer end portions 15 which are partly embedded in the pinch seals 14 and project endwise therefrom and are sufficiently rigid to support the lamp 10. The bulb is provided with a glass exhaust tubulation 16 which projects from the side of the tubular bulb 11 more or less midway of the length thereof and through which the bulb is evacuated and gas filled during the manufacture of the lamp 10. After such evacuation and gas filling, the exhaust tubulation 16 is hermetically sealed or tipped-off as indicated at 17 by heat softening and collapsing it as close as possible to the bulb 11. As shown, the lamp 10 is mounted in the glass outer envelope 1 with its tubular bulb 11 and longitudinally extending filament coil 12 disposed transversely to the optical axis of the reflector surface 6 approximately in the focal plane thereof, and with the filament coil 12 approximately centered at the focus of the reflector surface 6 so that the coil axis intersects the reflector axis A. Also, as shown, the lamp 10 is mounted in the envelope 1 with its flat pinch seal ends 14 disposed parallel to the axial plane of the reflector section 2 which includes the axis of the tubular lamp 10, and with the exhaust tip 17 of the lamp 10 projecting rearwardly toward the apex region of the reflector section 2. In this way, the flat pinch seals 14 and the exhaust tip 17 interfere as little as possible with the passage of light rays from the lamp 10 to the reflector surface 6 and out the clear glass front 3 of the device.

In accordance with the invention, the compact electric lamp 10 is supported within the outer enclosing envelope 1 from three triangularly disposed wire supports comprising a pair of combination current-supply and support Wires 18 and 19 and a third or additional support wire 20. The three support wires 18, 19 and 20 extend into the envelope 1 from the apex region of its reflector section 2 in a direction generally parallel to one another and to the reflector axis A and in triangularly disposed relation thereabout, with the two current-supply wires 18 and 19 located on opposite sides of the reflector axis A and disposed approximately in that axial plane of the reflector section 2 which includes the axis of the tubular bulb 11 and filament coil 12 of the lamp 10. The third wire support 20 is located to one side of the axial plane of the reflector axis A which includes the tubular lamp 10 and current-supply wires 18, 19, and it is preferably located approximately in an axial plane of the reflector surface 6 normal to the plane of the current-supply wires 18, 19 so that the three support wires 18, 19 and 20 together define, in effect, the three corners of an isosceles triangle the base of which intersects the reflector axis A.

The three support wires 18, 19 and 20 for the lamp 10 extend through respective through-passageways or openings 21 in the wall of the reflector section 2 of the outer envelope 1 to the exterior thereof where they are electrically connected to, and fixedly supported from the wall of the reflector section by respective metal ferrules or thimbles 22 anchored in the glass of the reflector section 2 around the respective openings 21 therein. The support wires 18, 19 and 20 are suitably fastened, as by a brazing alloy as shown at 23, to the closed nippled outer ends 24 of the respective metal ferrules or thimbles 22. The ferrules 22 are formed of a suitable metal, such as a nickel-iron alloy, which will wet and adhere to the glass of the reflector section 2, and they are provided with thin-walled skirt portions 25 feathered to knife-edged rims which are embedded and fused in the glass of the reflector section 2 around the respective openings or passageways 21 therein. The two metal ferrules 22 to which the current-supply wires 18 and 19 are fastened are provided with respective metal terminal contacts in the form of metal straps or lugs 26 which are suitably fastened, as by soldering for instance, to the closed nippled ends 24 of the ferrules. The contact lugs 26 are provided with screw terminals 27 for connection to an electric power supply.

Interiorly of the outer envelope 1, the two current-supply wires 18, 19 are bent oppositely away from each other to form offset inner end portions 28 disposed approximately in the plane of the tubular lamp 10 and its flat pinch seal ends 14 and extending alongside the endwise facing outer edges of the respective pinch seals 14 of the lamp 10 so as to, in effect, straddle the lamp 10. At their inner ends, the offset portions 28 of the current-supply wires 18, 19 are rigidly connected to the rigid outer end portions 15 of the lamp lead-in conductors 13 to thereby rigidly support the lamp 10 in place in the outer envelope 1 between the offset inner end portions 28 of the current-supply wires 18, 19.

In accordance with the invention, the lamp 10 is additionally supported in place within the glass outer envelope 1, against excessive vibratory movement therein, by a pair of rigid insulating brace or bridge members 29 rigidly connected at one end to the inner end of the third support wire 20 and at their other ends to respective ones of the current-supply wires 18, 19 adjacent their connections to the outer portions 15 of the lead-in conductors 13 of the lamp 10. The third support wire 20 with its associated brace members 29 thus together form additional support means for the lamp 10. As shown, the brace members 29 each comprise a glass rod 30 having a pair of spud wires 31 embedded in and projecting endwise from each end thereof, the two spud wires 31 at the respective ends of the brace members 29 being respectively welded to the support wire 20 and to the offset inner end portions 28 of the current-supply wires 18 or 19 adjacent their connections to the outer lead portions 15 of the lamp lead-in conductors 13. Also as shown, the two brace members 29 are secured to the third support wire 20 at points spaced inwardly of the reflector member 2 relative to the lamp 10 therein so as to extend angularly inward of the reflector member 2 from their points of connection to the currentsupply wires 18, 19. In this -way, the brace members 29 are located substantially out of the path of travel of those light rays emitted by the lamp 10 which are directed generally transversely to the axis of the reflector surface 6 and so offer the least possible amount of interference to the passage of all that light from the lamp directed toward the reflecting surface 6. For the same reason, the third support wire 20 is terminated short of the lamp 10.

To rigidify the supporting structure for the lamp 10 and maintain the support wires 18, 19 and 20 in fixed relation to each other, suitable insulating bridges or brace members 32, 33 and 34 may be connected across respective pairs of the said support wires to insulatively and rigidly tie them together, as shown. The said bridges or brace members may be of the same type employed for the brace members 29 and comprising a glass rod 30 having a pair of spud wires 31 embedded in each end thereof and welded to the adjacent support wires 18, 19 or 20.

By providing a supporting structure for the electric lamp of the tripod-like form shown and described, a light projection device is produced in which the resonant frequency of the lamp mount, i.e., the combined lamp and support structure therefor, is substantially higher than if the lamp 10 were merely supported at its opposite ends across the two current-supply wires 18, 19. As a result, for the same G loading, the amplitude of the vibratory movement of the lamp filament 12 which occurs when the light projection device is subjected to severe vibration such as encountered in modern high-speed jet aircraft service, is considerably decreased. With such a decreased amplitude, the filament 12 therefore has a lower moment of inertia and thus is not subjected to as much distortin force and consequent likelihood of rupture.

By the use of the mount construction according to the invention, the life of light projection devices for aircraft landing beam service has been increased by a factorfof at least six over conventional type aircraft landing lamps, while maintaining the same initial maximum beam candlepower and wattage of the device. In addition, the maximum beam candlepower of light projection devices according to the invention at 70% of design life, i.e., the maintenance thereof, is approximately 85% of the initial maximum beam candlepower, as contrasted to a maintenance of only 50% for previous type aircraft landing lamps in which the light source is constituted simply by a tungsten coil filament mounted within the envelope 1. Because of its greatly increased life and improved light maintenance as compared to such prior conventional type aircraft landing lamps, the light projection device according to the invention therefore is much more superior for use in aircraft landing beam service, especially since it greatly reduces the frequency of lamp replacement necessitated by lamp failure.

Although a preferred embodiment of my invention has been disclosed, it will be understood that the invention is not to be limited to the specific construction and arrangement of parts shown, but they they may be widely modified within the spirit and scope of my invention as defined by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A light projection device comprising a reflector member having a concave reflector surface formed as a surface of revolution about an axis, a compact electric lamp mounted in said reflector member and comprising a sealed double-ended envelope containing a light source and having a pair of lead-in conductors sealed into and provided with rigid outer end portions extending outwardly from the opposite ends of the envelope, said lamp being mounted in said reflector member with its envelope ends disposed transversely to the axis of said reflector surface and with its light source located adjacent the focus thereof, a pair of rigid current-supply wires fixedly secured to the wall of said reflector member and extending thereinto approximately in an axial plane thereof including the said outer end portions of the lead-in conductors, said current-supply wires being rigidly connected to the outer portions of the said lead-in conductors of the lamp to thereby support the lamp in place in the reflector member, and additional support means for said lamp comprising a rigid support wire fixedly secured to and extending through the wall of said reflector member in triangularly disposed relation to said current-supply wires, and a pair of rigid insulating brace members fixedly secured at one end to said support wire and at their other ends to respective ones of said current-supply wires adjacent their connections to the said outer end portions of said lamp lead-in conductors.

2. A light projection device as specified in claim 1 wherein the said brace members are secured to the said support wire at points spaced inwardly of the reflector member relative to said lamp and extend angularly inward of the reflector member from their points of connections to the said current-supply wires so as to be substantial- 1y out of the path of light rays emitted by the lamp directed generally transversely to the axis of said reflector surface.

3. A light projection device as specified in claim 2 having additional rigid insulating brace members fixedly secured to and respectively rigidly tying the said currentsupply wires to the said support wire.

4. A light projection device as specified in claim 2 having additional rigid insulating brace members fixedly secured to and respectively rigidly tying the said currentsupply wires together and to the said support wire.

5. A light projection device as specified in claim 1 wherein the portion of said support wire connected to the said brace members is located approximtaely in an axial plane of said reflector surface normal to the plane of said current-supply wires.

6. A light projection device as Specified in claim 1 wherein the said electric lamp comprises a halogen-cycle incandescent lamp the envelope of which contains a halogen and the light source of which comprises a tungsten filament connected at its opposite ends to the said leadin conductors.

7. A light projection device comprising a reflector member having a concave reflector surface formed as a surface of revolution about an axis, a compact electric lamp mounted in said reflector member and comprising a sealed double-ended envelope containing a light source and having a pair of lead-in conductors sealed into the envelope through flat pinch seal end portions thereof disposed in a common axial plane of said envelope, said leadin conductors being provided with rigid outer end portions extending outwardly from the pinch seal ends of the envelope, said lamp being mounted in said reflector member with its said flat pinch seal ends disposed transversely to the axis of said reflector surface and in an axial plane thereof and with its light source located adjacent the focus of said reflector surface, a pair of rigid current-supply wires fixedly secured to the Wall of said reflector member and extending thereinto approximately in an axial plane thereof including said flat pinch seal ends of said envelope, said current supply wires being rigidly connected to the outer portiofis of the said leadin conductors of the lamp to thereby support the lamp in place in the reflector member, and additional support means for said lamp comprising a rigid support wire fixedly secured to and extending through the wall of said reflector member in triangularly disposed relation to said current-supply wires, and -a pair of rigid insulating brace members fixedly secured at one end to said support wire and at their other ends to respective ones of said current-supply wires adjacent their connections to the said outer end portions of said lamp lead-in conductors.

References Cited UNITED STATES PATENTS 2,791,713 5/1957 Dean 313-113 2,883,571 4/ 1959 Fridrich et a1. 313179 3,364,378 11/ 1968 Beesley 313-113 JAMES W. LAWRENCE, Primary Examiner.

DAVID OREILLY, Assistant Examin er.

US. Cl. X.R. 

